1. Field of the Invention
There are currently two types of service vehicles being manufactured for the purpose of transporting disabled automobiles or other vehicles not suitable for transportation on the highways. These service vehicles are the tow-truck, and the vehicle carrier. This invention relates to vehicle carriers in general, commonly known and herein referred to as car carriers, and more particularly to a two car carrier capable of loading a first car onto a platform that also provides apparatus for towing a second car behind.
2. Description of the Prior Art
Car carriers of the prior art accomplish loading by various means. One means is to slide a platform back within guides of a subframe pivotally coupled to the rear of the service vehicle frame and to tilt the subframe and connecting platorm into engagement with the ground to form a loading ramp up which cars may be pulled or driven. Support feet rigidly attached to the tilted subframe contact the ground and provide intermediate platform support. Car carriers of this type are characterized by a number of objectional features. Among those are: the support feet are not well adapted to uneven ground contact relative to ground contacted by the rearmost edge of the tilted platform or by the wheels of the service vehicle; the susceptibility of damage to the service vehicle by operator error whereas premature tilting of the subframe will disengage the support feet allowing an extended platform to cantilever from the frame of the service vehicle causing damage thereto; and platform positioning being a two step procedure whereby first the platform is tilted and second the platform extended.
Another means for loading is disclosed in the Grove patent, U.S. Pat. No. 3,430,792, wherein a platform slides back and pivots on a fixed pivot at the rear of the service vehicle frame where also one end of an apparatus for tilting the platform is pivotally coupled that includes a pair of hydraulic jack support feet having first ends in sliding engagement with the platform and second ends that contact the ground. Car carriers of this type cannot damage the frame of the service vehicle yet are also characterized by a number of objectional features. Among those are: the two hydraulic jack support feet of the tilt apparatus act as a unit and are therefore not well adapted to contacting substantially uneven ground relative to each other; the rear wheels of the service vehicle can be uplifted if the load's center of gravity is towards the rear of an extended platform as it is to be tilted; and the platform positioning is a three step procedure whereby first the tilt apparatus is lowered into ground contact, second the platform is extended, and third the platform tilted.
Still another means for loading is disclosed in the Ezolt patent, U.S. Pat. No. 3,450,282, wherein a platform is simultaneously slid back and tilted on a fixed rear pivot by extendable couplers having first ends pivotally coupled to the frame of the service vehicle and second ends pivotally coupled to the forward headboard end of the platform. Car carriers of this type are able to position the platform in a one step procedure yet are also characterized by a number of objectional features. Among those are: the platform positioning path is not specified thus requiring path compensation by varying the length of the couplers which are of complex construction; intermediate platform support feet are not provided thus requiring heavier platform construction that reduces payload while also subjecting the rear of the service vehicle frame to high stresses and damage thereto when an extended platform cantilevers from the frame during positioning; and a rear bumper is not provided as required by regulations governing highway vehicles.
A further means cited for loading is disclosed in the Forsythe patent, U.S. Pat. No. 3,159,294, wherein couplers of fixed length simultaneously tilt and slide a platform back within guides of a subframe pivotally coupled to the rear of the service vehicle frame. Support feet rigidly attached to the tilted subframe contact the ground and provide intermediate platform support. Car carriers of this type are able to position the platform in a one step procedure, provide support feet, include a bumper, and do not require couplers of complex construction yet are also characterized by a number of objectionable features. Among those are: a subframe is required; the support feet will only contact the ground when the platform is in load position and serve no purpose during any interval of platform positioning thus requiring heavier platform construction that reduces payload while also subjecting the rear of the service vehicle frame to high stresses and damage when an extended platform cantilevers from the frame during positioning; the support feet are not well adapted to contacting uneven ground relative to ground contacted by the rearmost edge of the tilted platform or by the wheels of the service vehicle; and the platform positioning path is not specified nor is it compensated, thus allowing the rearmost edge of the platform to contact the ground prematurely which can prevent the platform from obtaining load position and advantages thereof, or cause the platform to dig in or scrape along the ground prior to obtaining the load position.
Still further objectional characteristics of the prior art include the relatively steep loading angle afforded by the platform in load position. Reducing the loading angle by only a few degrees significantly improves the ramping of cars onto the platform. However, platforms of the prior art are of a single surface plane, that is, a flatbed; thus only by lengthening the platform can the loading angle be improved as the rear wheels of the service vehicle prevent the forward headboard end of the platform from being lowered further. Also, car carriers that include a second car tow apparatus must provide a reasonable distance between the rear of the platform and the towed car to allow clearance for turning corners. However, this reasonable distance places the towed car a further cantilever distance from the rear wheels of the service vehicle substantially increasing the load on same thus decreasing car carrier payload. Additionally, the platform decks of the prior art typically consist of plates welded to crossmembers. These plates are difficult to handle during fabrication and require considerable welding to construct a platform, with speciality welding a necessity when lightweight materials are used. Furthermore, the majority of prior art car carriers require considerable reinforcement of the service vehicle frame to offset the objectional design characteristics previously mentioned and allow their safe operation. Other frame alterations often include clearing or relocating existing frame crossmembers to eliminate interference with elements of the platform positioning mechanism, and lengthening of the frame and driveshaft to increase the wheel base of the service vehicle thereby affording better front and rear wheel weight distribution to increase payload.